The present invention relates to a machine hereinafter called xe2x80x9cloin pullerxe2x80x9d for trimming off the fat from the back of a loin, in particular a pork loin, without having to completely cut and separate the loin from the central part of the carcass-half of the animal.
As shown in FIG. 1 of the accompanying drawings, the central part of the carcass-half of a piece of meat comprises two main parts respectively called xe2x80x9cloinxe2x80x9d and xe2x80x9cflankxe2x80x9d. The loin is adjacent to the cut portion of the spinal column. The front portion of the loin contains ribs which are called xe2x80x9cback ribsxe2x80x9d after processing. In the rear portion of the loin is located the tender loin. The flank which is also called xe2x80x9cbellyxe2x80x9d, is the part which is adjacent to the loin at the opposite of the spinal column. The ends of the ribs which extend along the flank can altogether be separated from the same to form xe2x80x9cspare ribsxe2x80x9d, or they can be removed individually. After removal of the ribs, the flank is mainly used to prepare bacon. The whole carcass-half is covered by an external layer of fat which extends under the loin and flank. The thickness of this layer of fat depends on several parameters including, inter alia, the size, the origin and the nutrition of the animal. This fat is the one that can be found in bacon. Therefore, it is important from a practical standpoint to keep a proper amount of fat with the flank prior to cutting the same. However, it is important to remove same of the fat extending under the loin to avoid an over load of fat in the final product.
For trimming the fat off the loin, use is made of automatized machines called xe2x80x9cloin pullersxe2x80x9d, which are used in the cutting sections of the industrial slaughter houses.
Prior to processing a loin in a loin puller, it is of course necessary to separate it from the flank. So far, there have been two different methods of doing so.
The first method, called xe2x80x9cCanadian cutxe2x80x9d, consists in completely separating the flank from the loin by completely cutting the carcass-half according to a suitable cutting line which may vary depending on the need. An example of such a cutting line is shown in dotted lines in FIG. 1. Such a cutting can be carried out either manually or by means of another machine located upstream the loin puller or within the same. Once separated, the flank can be directed towards another machine or another working table specially adapted for this purpose, in order to separate the spare ribs. On the other hand, the loin is introduced into the loin puller, in order to trim off its fat.
A non-limitative example of loin puller specially adapted for processing loins after full separation from the adjacent flanks is disclosed in U.S. Pat. No. 5,090,939 issued on Feb. 25, 1992 in the name of the Applicant.
The second method, called xe2x80x9cAmerican cutxe2x80x9d, consists in cutting (scribing) only the internal part of the carcass-half, that is the upper part of the carcass-half shown in FIG. 1, following the same type of cutting line as above, except for the fat. As a result, the layer of fat remains uncut and maintains altogether the loin and the flank. Then, both of them may be transferred together to a working table where the loin is processed to remove part of the layer of fat from the loin. The main advantage of this method is that it makes it possible to recover part of the fat and meat of the loin together with the flank, which part would otherwise have been left onto the loin and trimmed off by a cutting blade. Usually, this method of processing carcass-halves is carried out manually, even though industrial machines have been proposed to do it.
Thus, for example, U.S. Pat. No. 5,295,898 issued on Mar. 2nd, 1994 in the name of ACRALOC CORP., discloses a loin puller especially adapted for processing carcass-halves having been subjected to an American cut. In this loin puller, each carcass-half is moved by two conveyors extending in parallel relationship towards a cutting zone where an arcuate blade which is preferably heated and whose height and curvature are adjustable, is positioned above the first conveyor supporting the loin for processing the same and trimming off its layer of fat. While the fat of the loin is cut, the flank is moved at the same speed along the second conveyor, which is positioned at the same level as the one of the first conveyor and may include another cutting zone where another knife cut the extra fat extending under the flank (see FIG. 3c of this patent).
In the loin puller disclosed in U.S. Pat. No. 5,295,898 as well as in all the other existing loin pullers used for processing carcass-halves having been subjected to an American cut, the loin and flank are maintained altogether in a same horizontal plane. Therefore, an operator provided with manual control means must very carefully follow the movement of the carcass-half to determine the optimum scribing line and to adjust accordingly the scribing saw while simultaneously adjusting the height of the cutting blade. Such requires much dexterity from the operator who must determine the scribing line and who has very few visual information to evaluate the thickness of the layer of fat and thus to adjust the height of the cutting blade. Indeed, the operator has no visual access to the layer of fat under the loin after the loin has been engaged by the cutting blade. The operator has also poor visual access to evaluate the position of the cutting blade relative to the ribs, because of the presence of the flank in horizontal position adjacent to the loin. As a result, the operating speed of the machine is reduced as compared to the loin pullers used for processing loins having been subjected to a Canadian cut.
A main object of the present invention is to solve the above mentioned problem by providing a loin puller which, thanks to its structure, permits to process carcass-halves having been subjected to an American cut in view of trimming the fat off the loin while simultaneously permitting to the operator or to a detection system to determine the thickness of the back ribs on the loin and the thickness of the meat, and thus to evaluate the upper level of the layer of fat under the loin, such allowing an evaluation of the optimum height for positioning the arcuate blade for trimming off the fat with or without the adjacent lean meat depending on the user""s requirement.
The invention is based on the discovery that, after scribing, by letting the flank fold down and hang on one side of the loin while said loin is moved by the conveyor towards the cutting zone instead of supporting the flank by means of another conveyor, it becomes possible for the operator or the detection system used for controlling the blade, to determine the level of the layer of fat under the loin and/or the thickness of the ribs and/or the position of the lean meat along the same, such allowing optimum adjustment of the position of the cutting blade.
Therefore, the present invention provides a loin puller for processing a carcass-half comprising a loin and a flank partially separated by scribing, said loin comprising a layer of fat of a given thickness to be trimmed off and lean meat adjacent said layer of fat. This loin puller is of the type comprising:
a frame;
an elongated rectilinear working surface fixed to the frame and intended to receive and support the loin of the carcass-half to be processed;
a conveying system mounted onto the frame above the working surface for engaging the loin, pressing said loin and moving said loin together with the flank connected thereto towards a cutting zone; and
an arcuate cutting blade mounted to the frame in the cutting zone for engaging the loin when the same is moved by the conveying system and cutting the layer of fat to be trimmed off the same, with or without lean meat on the trimmed fat attached to the flank.
In accordance with the invention, this loin puller is improved as compared to the existing loin puller in that its frame is devised to let the flank fold down and hang from the working surface while the carcass-half is moved by the conveying system, whereby more visibility is left for an operator to evaluate an optimum cutting position for the cutting blade and more spacing is left between the cut ribs once the flank is folded down from the loin, thereby making the loin puller operable manually or automatically from any side and position along the frame.
This invention is quite simple and very efficient, as tests carried out by the Applicant have shown it. The invention is also interesting in that it can be carried out by properly adapting the structure of existing loin pullers, like the one disclosed in U.S. Pat. No. 5,090,939 mentioned hereinabove, in the name of the Applicant.
Of course, the frame of the loin puller must be devised to allow the flank to fold down and move together with the loin to which it is attached.
Advantageously, guides in the form of plates and/or rigid tubes of metal can be provided at the inlet and along the machines to force the flank to fold down and hang relative to the loin. Such may be necessary when the carcass-half to be processed is very cold and rigidified by cooling or for other reasons.